A performance analysis, which measures such statistical traffic data as an amount of transferred data, becomes important according to a spread of the Internet. As described in Japanese Patent laid-open Application No. 11-252111, the inventors considered that it was possible to recognise a situation of the Internet by measuring a TCP-level statistical information (for example, an amount of re-transferred data, a waiting time for establishing a connection etc.), then developed a traffic monitor which can collect the TCP-level statistical traffic information in addition to an IP-level information by monitoring a backbone line of the Internet. The traffic monitor was developed under such a condition that it was possible to monitor segments of both directions in a TCP communication on the same line.
However, as an IP routing is controlled according to each direction, there is a case that traffics of both directions do not flow on the same line. Namely, because it can be considered that a going route and a return route are different each other in a real network configuration, there is a case that traffics of both direction can not be captured.
It is known the MRTG technique for collecting IP-level statistical traffic information such as an amount of segments per a unit time or an amount of bytes per a unit time respectively in a router. Further, it is known the SNIFFER technique for collecting TCP-level statistical traffic information such as an amount of segments or an amount of bytes respectively at every application in addition to the IP-level statistical traffic information. However, each technique has a condition that it is possible to monitor segments of both direction in the TCP communication on the same line.
An object of the present invention provides a method for collecting, by managing the TCP-level information in a certain direction, at least a traffic in another direction where it is impossible to directly capture the traffic.